Given the various advantages of HAPS systems in providing connectivity from the sky, this article investigates the role of HAPS as a cloud computing and communication platform (i.e., cloud-enabled HAPS). The proposed architecture provides a cost-effective connectivity solution to users in rural and isolated regions while ensuring a stable connection to users in urban areas [1]}.
Moreover, the HAPS cloud in our work is assumed to be connected to disjoint clusters of both hot-air balloons and terrestrial BSs via high-speed yet finite FSO fronthaul links, where the coordination of the mutual transmission strategies occurs across the BSs within one cluster. Our work further assumes that aerial users (e.g., LAPS, drones) are exclusively served by the hot-air balloon clusters, which is a practical design consideration since serving aerial users using terrestrial BSs requires full-dimensional antenna arrays [2]}, [3]}. Terrestrial users, on the other hand, can be served by hot-air balloon clusters or terrestrial BS clusters.
Assuming a spatial multiplex system in the downlink direction using beamforming, this work optimizes the user-to-transmitter association strategy, jointly with the beamforming vectors, subject to per-BS fronthaul capacity and transmit power constraints. In particular, this article studies two different optimization problems inspired by the need to create a digital equity paradigm. We next highlight the contributions of each considered problem in its own right.
